Photographic printing apparatus



Nov. 3, 1953 E. J. MAKER ET AL PHOTOGRAPHIC PRINTING APPARATUS FiledJan. 29, 1947 8 Sheets-Sheet l "HIV ul ,ul

INVENTORS EDWIN J. MAKER JAM S L.GIB

I N Q ATTO EY Nov. 3, 1953 E. J. MAKER ET AL 2,657,613 PHOTOGRAPHICPRINTING APPARATUS Filed Jan. 29, 1947 8 Sheets-Sheet 2 INVENTORS EDWINJ. MAKER JA ES .s| ON BY Q, 5,

ATTO NEY Nov. 3, 1953 Filed Jan. 29, 1947 E. J. MAKER ET AL PHOTOGRAPHICPRINTING APPARATUS 8 Sheets-Sheet 3 INVENTORS EDWIN J. MAKER Nov. 3,1953 E. J. MAKER ET AL 2,657,613

PHOTOGRAPHIC PRINTING APPARATUS Filed Jan. 29, 1947 8 Sheets-Sheet 4FIG-5 INVENTORS EDWIN J. MAKER J E5 L. G SON BY Q.

ATT RNEY Nov. 3, 1953 E. J. MAKER ET AL 2,657,613

PHOTOGRAPHIC PRINTING APPARATUS Filed Jan. 29, 1947 8 Sheets-Sheet 5FIG. l2

INVENTORS EDWIN J. MAKER JA ES L. BY 3.43 5v ATT RNEY Nov. 3, 1953 FiledJan. 29, 1947 FIG. l5

E. J. MAKER ET AL PHOTOGRAPHIC PRINTING APPARATUS 8 Sheets-Sheet 6 I 4 V9 2 22 27 4 QM/m7 29 INVENTORS EDWIN J. MAKER JA 5 L. 6 BS N ATTOR EYNov. 3, 1953 E. J. MAKER ET AL PHOTOGRAPHIC PRINTING APPARATUS 8Sheets-Sheet 7 Filed Jan. 29, 1947 INVENTORS EDWIN -J. MAKER JA ES L.Glso ATTORNEY NOV. 3, 1953 E. J. MAKER ET AL 2,657,613

PHOTOGRAPHIC PRINTING APPARATUS Filed Jan. 29, 1947 s Sheets-Sheet 84INVENTORS EDWIN J. MAKER JAM s L.GIBS',,- BY 6, I I, I? v TT NEYPatented Nov. 3, 1953 PHOTOGRAPHIC PRINTING APPARATUS Edwin J. Maker andJames L. Gibson, Chicago, Ill., assignors to Walgreen 00., Chicago,111., a corporation of Illinois Application January 29, 1947, Serial No.725,049

Claims. 1

This invention relates to photography and particularly to a photographicprinting apparatus for automatically making prints from negatives,although certain features thereof may be employed with equal advantagefor other purposes.

It contemplates more especially the provision of an improved and moreefiiciently operated photographic printing apparatus wherein properlyexposed prints may be reproduced from negatives on a high productionbasis.

In the photographic art it is customary, in making prints fromnegatives, to use a grade of contrast paper which is consistent with thetype of negative from which a print is to be made. For example, if thenegative to be printed is fiat or weak, a relatively hard grade of paperis used for printing and, conversely, if the negative is hard orcontrasty, a relatively soft grade of paper is used for printing. By thepresent invention it is proposed to provide a photographic printingapparatus equipped with an electrically controlled means which includesa plurality of resistance control circuits as representative of adifference in the relationship between the principal subject and theaverage mean density of the background. The resistance control circuitsare in reality a series of electrical paths or branches which are partof a main circuit, one of which may be chosen for operation. Morespecifically, each of said resistance control circuits would be providedwith a switch, selectable by the judgment of an operator and indicativeof the relationship between the principal subject and the background andfor the purposes of control, these electronic circuits havingarbitrarily been divided into five exposure control groups; namely,

extra short, short, normal, long and extra long.

The operation of a chosen control switch selects the resistance circuitmost desirable for the negative being printed and thereby establishes aninitial control for the time of printing exposure. But the time ofprinting exposure is controlled by the average light transmissioncharacteristics of the negative itself. With the arrangement justoutlined above, only a single grade of paper is employed for printingpurposes, compensation for principal subject area relationship tobackground of the negative being made by the electrical control meansmentioned above.

One object of the present invention is to provide a photographicprinting apparatus for automatically making prints irom negatives.

Another object of the invention is to provide in an automatic printingapparatus a plurality of controls, one of which may be selected foroperation dependent upon the light transmission characteristics of thenegative from which a print is to be made.

Still another object of the invention is to provide in a photographicprinting apparatus a plurality of control means for establishing aninitial control for the time of printing exposure, one of which may beselected for operation dependent upon the light transmissioncharacteristics of the negative to be printed, and further control meansdirectly responsive to the light transmission characteristics of thenegative itself for finally determining the time of printing exposure.

An additional object of the present invention is to provide in aphotographic printing apparatus means for obtaining an integration ofthe light transmission characteristics of a negative and utilizing saidintegration to control the time of printing exposure.

A further object of the invention is the use of an out-of-focus image ofa negative as a timing control medium for print exposure.

A still further object of the invention is to provide in a photographicprinting apparatus, means for automatically reproducing a predeterminednumber of positive prints.

Still a further object of the invention is to provide in a photographicprinting apparatus an adjustable feed means for feeding a predeterminedlength of printing paper.

An additional object of this invention is to provide a photographicapparatus which integrates the negative and determines the properexposure, electronically, and at the completion of the exposure cycle,automatically and electronically cuts off the printing light and engagesthe necessary mechanism for advancing the photo paper a predeterminedamount necessary for additional prints, and at the completion of thefeeding of the photo paper, resets the electronic timer preparatory forthe next exposure.

A further object of this invention is to provide electronicallycontrolled means for interlocking the mechanical and electricaloperations in such a fashion that double exposures on a single sheet ofprinting paper are impossible.

Another object of this invention is to provide an electro-mechanicalcontrol means for a photographic printing apparatus operable by switchmeans which initiate an exposure operation, automatically terminates theperiod of print exposure, and feeds a new section of print paper intoprinting position.

A still further object of this invention is to provide suitableadjustments for presetting the timer control elements to producecomparable results on photo paper of different exposure timecharacteristics.

Other objects, features and advantages, while not specifically set outabove, will appear as the invention is described in detail.

As previously mentioned, the photographic printing apparatus is equippedwith a plurality of control circuits selectable according to thetransmission characteristics of a negative being printed at a particulartime. These resistance control circuits are associated with a capacitorwhose discharge rate determines the time of printing exposure. Prior tothe selection of a particular circuit, the operator judges thetransmission 'characteristics of the negative by placing the negativeover a judging glass. A proper control switch is then depressed which iseffective in conditioning the chosen circuit for operation. Analternating current control relay is first operated by manuallydepressing the operating switch and its operation enables a direct current relay to be operated by means of an electronic circuit. Operationof the direct current relay provides a locking circuit for the controlrelay and operates a printing light relay and I transfer relay. Inaddition thereto, operation of the direct current relay is effective incausing the energization of a solenoid which operates a platen to holdthe printing paper in a fixed position during the exposure period. Ajudging shutter k solenoid is also under the control of the directcurrent relay and insures the closing of the judging shutter prior tothe operation of the prin ing light in order to prevent glare in theeyes of the operator. Further, the direct current relay controls theoperation of the printing light which is situated in a compartment underthe table of the machine and this light is transmitted by an opticalsystem and suitable mirrors through the negative by another opticalsystem, whereby the enlarged image of the negative is projected on thesensitive surface of the photo paper. Further, the direct current relaycontrols the operation of a light shutter interposed between theprojection lens and the sensitive paper, opening this shutter at thesame instant the light is turned on to maximum brilliance. Operation of.1

the transfer relay effects the operation of a clutch control relay. Theclutch, however. does not operate until the termination of the exposureperiod.

When the operating switch is depressed, it closes a predeterminedresistance circuit and places it in circuit across a condenser which atthis time becomes charged. Above and on" center from the main light rayspassing through the negative is a lense so positioned that it picks upan image of the negative to be printed and projects an out-of-focusimage on the cathode of a photo-electric cell with which it isassociated.

The result of this positioning of the lens is the throwing of anout-of-focus image upon the cathode which is an integration of the lightconducting characteristics of the negative. The advantage of thisout-of-focus image is important since it causes a blending together ofthe light transmitting characteristics of various parts of the negative.On the other hand, if the lens where in focus, a sharp image wouldimpinge upon the light sensitive cell and negatives having areas oflesser density than other areas, such areas being capable oftransmitting greater quantitles of light, could impinge upon a portionof the cathode whose sensitivity to light would be conceivably moresensitive than other sections of the cathode, thus providing anunreliable control medium. The control medium thus obtained is utilizedin the final determination of the time of printing exposure. The cathodeof the photocell becomes conductive in proportion to the in- 4 tensityof the light as determined by the aforementioned integration which, inturn, determines the discharge rate of the capacitor previouslyidentified, over the selected resistance circuit.

Discharge of the condenser operates suitable control means whichextinguish the printing light, release the platen, close the lightshutter and open the judging shutter. It'further enables the operationof a single revolution clutch associated with a mechanical photo paperfeed mechanism. Means are also provided for automatically reproducing apredetermined number of prints by causing a recycle of operationsaccording to the number of prints desired.

The invention may be more readily comprehended by reference to thedetailed description which follows when read in conjunction with thedrawings in which:

Figure 1 is a front elevational view of the printing apparatus,

Figure 2 is a rear elevational view of the photographic printingapparatus,

Figure 3 is an enlarged detailed left end view of the main operatingmechanisms of the apparatus,

Figure 4 is an enlarged detailed view of the cam switches utilized inthe present invention,

Figure 5 is an enlarged detailed plan view of the platen for holding theprinting paper,

Figure 6 is a left end view showing the platen and the light shutter,

Figures 7 and 8 are detailed views of the light shutter showing theclosed and open positions, respectively,

Figure 9 is a detailed plan view of the treadle used for operating thenegative holding mask.

Figure 10 is a detailed plan view illustrating particularly the negativeholding mask.

Figure 11 is a detailed view of the drag brake used in conjunction withthe printing paper supply reel,

Figure 12 is a detailed view showing portions of the adjustable paperfeed and the clutch operating mechanisms.

Figure 13 is a fragmentary perspective view of the single revolutionclutch used in the present invention,

Figure 14 is a detailed view of a portion of the clutch mechanism,

Figure 15 is a schematic illustration of the light projection systemused in the present invention,

Figures 16 and 17 are circuit diagrams of the proposed invention.

Figure 18 shows the arrangement of the circuit comprising Figures 16 and17,

Figure 19 is a detailed view of the friction clutch adjusting mechanism.

Referring now to the drawings, the invention will be described indetail. In Figure 1, numeral ill represents a stand upon which ismounted a vertically extending framework or housing which is indicatedgenerally at I I. On top of the frame (as best illustrated in Figure 2)is mounted a motor l2 which, by means of a suitable belt and pulleyarrangement, drives shaft 14 in a clockwise direction, as shown in thesame view. Shaft l4 carries at its front end (as best shown in Figure 3)driving gear l6, which drives the large gear I! fast to shaft 18. To therear of shaft I8 is attached a gear 19 which is in mesh with, the largegear 2| and drives the latter gear in a counterclockwise direction, asviewed from the front of the machine. Gear 2|, by means of its hub 22,is rotatable about shaft 28 and through the instrumentality of afriction slip clutch 24,

drives the paper take up reel 26. This is accomplished as the frictionclutch 24 drives the collar 21, whose reduced portion 28 is attached toshaft 29, to the other end of which is connected, by means of hub 3I,the take up reel 25.

In Figure 19 is shown a clutch adjusting mechanism for the frictionclutch 24 for varying the friction between friction plate 3 and collar21. Shaft 29 is internally threaded at 4 and receives the adjustingscrew 5 which presses against coil spring 6. Coil spring 6 in turnpresses against slide 1 which carries a pin 8 which moves in the.diametrically opposite slots 9 of shaft 29. The ends of pin 8 are madefast to collar I5 which moves with gear 2I and hub 22. It is apparentthen, that by turning the adjusting screw 5. the pressure between plate3 and collar 21 may be varied and screw 5 may be held in adjustedposition by a lock nut 25.

Carried on shaft i8 near the front of the apparatus is a ratchet wheel32 which constitutes the driving part of a clutch indicated generally as33 in Figures 12 13 and 14. The clutch 33 is controlled from the plunger34 of clutch solenoid 36. Pivotally attached to the plunger 34 at 31 isa bell crank lever 38 which, in turn, is movable about the pivot 39. Thedownwardly extending arm M of the bell crank lever 33 is provided with aslot 42 near its lower end, through which projects a pin 43, carried bythe lower arm 44 of clutch stop lever 46, which is also pivoted at 39. Ashoulder 41 formed at the free end of the clutch stop lever 45 isnormally positioned (in the rest position of the clutch) to hold a latchpawl *48 in a clockwise position against the action of retractile spring49. The latch pawl 48 is mounted at 5| on the relatively large circularplate 52 and the foregoing action of stop lever 46 on the latch pawl 48is efiective in maintaining the hooked shaped portion 53 out ofengagement with the constantly rotating ratchet 32 previouslyidentified. The stop lever 46 carries a pin 54, designed to engage theshoulder 56 of latching lever 51, which is also pivoted on the axis 39and connected to lever 35 by spring 59. Latching lever 51 includes ahooked end 53 normally in engagement with shoulder 59 of block 8| whichis secured to the plate 52. The purpose of latching lever 51 is toconstrain plate 52 from clockwise rotation.

It can now be seen that, as the plunger 34 moves downwardly upon theenergization of solenoid 36, bell crank lever 38 is pivoted in acounterclockwise direction. This causes the slot '32 to engage the pin43 of stop lever 45, rotating the stop lever 45 likewise in acounterclockwise direction and removing the shoulder 4'? from blockingengagement with the pawl 48, which is now free to pivot at 5! in acounterclockwise direction under the influence of spring 49 to cause itshooked end 53 to engage the next passing tooth of ratchet 32. The justdescribed. action causes the rotation of the plate 52 and itsassemblage. It further can be seen that as stop lever 46 movescounterclockwise, its pin 54 will have engaged shoulder 55 of latchinglever 51 to also pivot the latter lever in a counterclockwise directionto remove its hooked end 58 from engagement with shoulder 59 of block 5I. As the plate 52 nears the end of a single revolution, solenoid 35will have become deenergized and stop arm 45 and latching lever 5'! willbe urged to their original posi tions by spring 49. Thus, shoulder 4'!will again engage latching pawl 48 and the hooked end 58 of stop lever51 will ride up the cam surface 62 of block BI and again become latchedupon the shoulder 59. A more detailed description of the operation of aclutch of this type may be found in the patent of R. F. Morrison, No.2,144,076.

Plate 52 is connected, by means of bolts 63 (Figure 3), to a plate 64carried by collar 66 which is freely mounted about the shaft I8. Bymeans of bushings 61 (three of which are shown in Figure 3) and suitablefastening means (not shown), switch cams 68, 69 and II carried on hubI2, and paper feed cam I3 are mounted for rotation with collar 65.Pivotally mounted about the shaft 29 is a lever 14, which carries at itslower end a gear segment It in mesh with gear I! mounted on shaft '58.Lever I4 carries a follower I9 which is in contact with the periphery ofpaper feed cam l3. Gear 1?, by means of a one way clutch 8| (details ofwhich are not shown) drives a pressure feed roller 82 in a clockwisedirection as viewed from the front of the apparatus in Figure 1. It isnow obvious that, as the clutch 33 is released, cam 13, by means of ahigh part thereof, will engage follower I9 to cause rotation of pressurefeed roller 82 as indicated, to feed the paper on to the take up reel2-6, since the paper is fed between pressure feed roller 82 and a fixedpressure roller 83. Normally, the pressure maintained on the printingpaper I00 between the rollers 82 and 83 is sufficient to hold take upreel 26 from rotation as the clutch 24 is caused to slip at this time.However, as a section of paper is advanced as explained, take up reel 26will rotate to take up the slack in the printing paper caused by thefeeding operation of the pressure feed roller 82.

The means for adjusting the feed mechanism to feed a predeterminedamount of printing paper will now be explained with particular referenceto Figure 12. By means of pin 84, lever I4 is connected to lever 85 andis pivoted therewith about the shaft 29. A spring 81 normally tends tohold lever I4 in a counterclockwise position as viewed in Figure 12. Toadjust the stroke of lever 14, there is mounted also about the shaft 29,adjacent to lever 86, an adjustable lever 88. The position of lever 83about the shaft 29 may be adjusted by means of a nut and bolt connection89 which may be moved to any desired position in slot 9| formed on theframework II of the apparatus. Lever 85, by means of a fiber roller 92,carried at the free end thereof, tends to follow a notch 93 ofadjustable lever 38. This action will determine the initial startingposition of the stroke and therefore will determine the amount of paperfed. It is obvious that, if nut and bolt connection 89 is moved to ahigher position in the slot 9|, less paper will be fed whereas, if it ismoved. to a lower position in slot 9|, more paper will be fed.

As the paper passes from the supply reel 94, it moves below a guideroller 96 (Figure 1) to the guideway 9'! of printing platen 98 which isunder the control of platen solenoid 99. When the solenoid 99 becomesenergized, its plunger IUI moves downwardly to also carry lever I92pivotally mounted thereto at I03 in a downward direction. Lever IE2 ispivotally mounted at I I9 to link I05 pivotally supported at I I5 onclevis I I5 and connected to platen 98 by link I20. The operation of thesolenoid is properly timed to hold the paper in a fixed position duringthe exposure period. At the termination of the exposure period, solenoid99 becomes deenergized and platen 98 is moved upwardly to free theprinting paper for the feeding operation. A flat spring I29 is placedunder thelever I02 which at the moment solenoid 99 is deenergized,raises the platen 98 upwardly.

At the start of the printing operation, the D erator places the negativeto be printed over a judging glass I04 (Figure through which light istransmitted by judging lights to be hereinafter identified. Operation ofthe judging light mask I06 will now be explained. When the operatordesires to place a negative beneath the mask I06, treadle I01 (Figure9), which is connected to a shaft I06 by means of rods I09 and III, isoperated downwardly against the tension of springs H2 and H3respectively connected to rods I09 and III. This moves the long rod II4,mounted for movement with shaft I08 by means of bracket H6, in adownward direction and further causes a lever I pivoted at I to theframework of the apparatus and connected to the upper end of rod I I4,to also move downwardly and to press against a rocker arm II1 to rotateshaft H8 in the bearings II 9 and I2I. Mask I06 is fixedly secured atI22 to the shaft H8 and by the aforementioned action is caused to moveupwardly enabling the operator to place the negative beneath the maskI06. The operator now removes his foot and the mask is returned to itsoriginal position by a spring I60, and the foot pedal is raised bysprings II2 and H3.

At the front of the apparatus is located a judging shutter I23 attachedby brackets I24 and I28 to a shaft I21 pivoted at I28 and I29 and urgedto an outward position normally by a coil spring I3I. With the shutterin its outward position, the operator may look over the top of theshutter to the judging glass I04 to determine the light transmissioncharacteristics of a particular negative. However, on operation of theapparatus, a solenoid I32 which is suitably connected to bent over armI33 of shaft I21 by a linkage not shown is energized, causing theshutter to pivot toward the rear of the apparatus, thereby closing itand preventing glare in the eyes of the operator from the printing lightto be hereinafter identified.

By particular reference now to Figures 6, '7 and i 8, operation of theprinting light shutter I34 will now be explained. When solenoid I36 isenergized, its/plunger I31 moves downwardly, causing links I38 and I39to be also moved in a downward direction. This pivots links MI and I42in opposite directions and causes pivotal rotation of their respectiveshafts I43 and I 44. Fixed to shafts I43 and I44 are their respectiveflaps I46 and I41 which, when solenoid I36 is energized (as in Figure8), move in opposite directions permitting light transmitted fromprinting light I 5| through optical system I59 to strike sensitizedpaper I00. When the links MI and I42 were caused to pivot as explained,they moved against the tension of associated springs I52 and I 53 whichcause flaps I46 and I41 to assume their original overlapping positions(Figure '7) upon deenergization of solenoid I36. It should be pointedout that the shafts I43 and I44 (Figure 6) extend out from the enclosureof the printing light shutter I34 and that links MI and I42 are mountedto the rear at the outside of the shutter enclosure itself.

Mounted within the printing light compartment I54 is the printing lightI5I previously referred to, lens I56, mirror I51, condensing lenses I58and heat absorbing glass I10. Also mounted on the apparatus, by meansnot shown, is a lens I59 which is positioned below the light shutterI34. Above and at the right side of the judging glass I04, as viewedfrom the rear of the apparatus is mounted a lens I6I which is in aD051.- tion to throw an out-of-focus image of the ne ative onto thecathode of a photoelectric cell I62. A drag brake I (Figure 11) isprovided on shaft I96, which carries printing paper supply reel 94, tomaintain tension on the printing pa per I00. It is adjustable by meansof a knurled member I91 to vary the constriction of block sections I98of the brake about shaft I96 to thereby vary the retarding pressure.Sections I98 are connected together by a spring plate 200.

Referring now particularly to Figures 16 and 17, the description of thecircuit operation will now be undertaken. To initiate the operation ofthe apparatus, a main switch 2| I is first operated which establishes acircuit for the judging lights 2l2 (only one of which is shown in Figure15,), the blower 2 I 3, paper feed motor I2, timer section 2 I 5 andpilot light 2| 6. It might be well to mention at the outset thefunctions of the parts just enumerated. The judging lights 2| 2 comprisetwo lamps mounted within the compartment I54 and are for the purpose ofenabling the operator to view the light transmission characteristics of.a negative from which a print is to be made and to accordingly selectthe proper control switch 220. The blower 2I3 is obviously provided forthe purpose of preventing overheating in the printing light compartmentI54. The motor I2 furnishes power for the cams involved in the mechanismwhich are controlled by the single revolution clutch 33. The timersection 2I5 which is in reality an electronic circuit controls the timeinterval for which a particular print will be exposed to lighttransmitted from the printing light I5I through a negative. Illuminationof pilot light 2I6 is an indication to the operator that the main switch2 has been operated.

The circuit for the judging lights 2I 2 and the blower 2i 3 is asfollows: from A. C. lead 224, over the conductors 226 and 221, throughmain switch 2II, over conductors 228, 229 and 23I, through obviousparallel circuits 232 and 233, over the conductor 234 to the A. C. line236. The motor I 2 is operated by the following circuit: from thecircuit extending from the conductor 234, to conductor 229 as previouslydescribed, through the motor I2 to the A. C. line 236. The circuitextending to the timer 2| 5 is made as follows: from the circuitpreviously described, extending over conductor 228 and over conductors24I, 242 and 234 to A. C. line 236. The circuit for the pilot light 2I6is as follows: from A. C. lead 224, through the primary winding oftransformer 243, over conductors 242 and 234 to A. (3. lead 236. Thissets up a current in the secondary of the transformer 243 and an obviousresulting circuit on leads 246 and 241 extending to pilot light 2 I6.

At this point the operator now selects and operates one of the controlswitches 220 in accordance with her judgment of the light transmissioncharacteristics of the negative from which a print is to be made, andthen operates switch248. After the operation of a selected controlswitch 220 but prior to the operation of switch 248, capacitor C-2 ischarged, due to the halfway rectifying action of tube v-n over thefollowing path: from A. 0. current extending to conductor 228 aspreviously described, through contact tongue 253 of relay 254, overconductor 256, through a variable resistor R-I, through parallelresistances R-I I, R-I II and Rr-IV and through one of the obviouscircuit paths established by the closure of one of the control switches226, over conductor 25! to one side of the capacitor C-2, thence, fromthe other side of the capacitor -2, to the grid of tube V-! I. to thecathode of the same tube, and to the conductor 24! which is associatedwith the opposite side of the A. C. power source, as was previouslymentioned in connection with the conditioning circuit for the timer 2I6.It might be mentioned that the control switches are of the type whereinone is always depressed, and the depression of a different controlswitch releases the one which was previously operated. Thus, for allpractical purposes, one control switch will always be depressed and thecapacitor C-2 may charge prior to the depression of the next controlswitch, it being understood that the rate of discharge of capacitor C-2is the controlling factor in determining the time of printing exposure.While resistance values are not herein given, it will be appreciated,for example, that the values will be such that upon operation of theextra short negative control switch the chosen circuit will be oneconducive to a relatively quick exposure, while on the other handoperation of the extra long negative control switch is one whichconditions a resistance circuit which tends to prolong the dischargerate of capacitor C-2. Final determination of the printing exposuretime, of course, is determined by the negative itself as previouslyexplained. It is believed that the individual resistance circuitsobtained by operating particular switches 226 are self evident and neednot be individually traced.

When the switch 243 is closed, A. C. relay 254 becomes energized overthe following circuit: From A. C. lead 236, over conductor 234, overconductor 242, through the winding of A. C. relay 254, over conductor258, through the switch I48, over conductor 259, through cam switch 26!(now closed), over conductor 262, through contact tongue 249 of A. C.relay 25!, over conductor 228, through main switch 2! I, over conductor221 and conductor 226 to A. C. lead 224.

Operation of A. C. relay 254 breaks the previously described chargingcircuit for capacitor C-2, which extended through contact tongue 253 asit now moves to its attracted position. Attraction of tongue 253 by A.C. relay 254 closes a circuit leading to the cathode of tube V-! i! asfollows: from the circuit previously described as extending from contacttongue 253, over conductor 263 to the cathode of tube V-! I This enablesdirect current to-flow in the plate circuit of tube V-!! I, due to therectifying action of tube V!V over the following path: from lead 264,through the winding of direct current relay 266, which now becomesenergized, over conductor 2'61, through milliammeter 268 of conductor269 which is maintained positive with respect to lead 264 due to theaction of rectifier tube V!V.

When D. C. relay 266 becomes energized, it attracts its armature tongue21! to provide a looking circuit for A. C. relay 254 a follows: from theA. C. current previously described as extending through conductor 252,through closed tongue 21!, over conductor 212, through the winding of A.C. relay 254 and over conductors 242 and 234 to A. C. lead 236.Operation of D. C. relay 266 causes it to also attract its contacttongue 213 which establishes circuits for the A. C. relays 214 and 216as follows: from A. C. lead 224, over conductors 226 and 221, throughclosed contact tongue 213, over conductor 211, through the windings ofA. C. relays 214 and 216 in parallel to conductor 24!, and thence overconductors 242 and 234 to A. C. lead 236. The energization of D. C.relay 266 and closure of its contact tongue 2E3 further enables theoperation of platen solenoid 69, the judging shutter solenoid !32 andlight shutter solenoid I36 as follows: from the circuit just describedextending through Contact tongue 213, over conductor 2H to the parallellead 2'58, thence through the respective windings of the solenoids tolead 219, over conductors 28! and 234 to A. C. lead 236. Thus, at thistime, the platen 98 firmly holds the printing paper I00 for the printingoperation, the printing light shutter 34 is opened and the judgingshutter I23 is closed preventing glare in the eyes of the operator whenthe printing light I5! becomes 11- luminated as will immediatelyhereinafter be described.

As A. C. relay 214 operates, a circuit is made for the printing lightI5! as follows: from A. C. current extending to lead 221, as alreadydescribed, through closed armature tongue 282 to A. C. relay 214, overconductor 283, through printing light I5! and over conductor 234 to A.C. lead 236.

When A. C. relay 216 operates, it causes the energization of A. C.ratchet relay 25! over the following path: from lead 221, through closedcontact tongue 284, over conductor 286, through the winding of A. C.ratchet relay 25! and over conductors 24! and 234 to lead 236. Thisratchet relay 25! is of the type wherein one energization closesassociated contacts by means of a cam rotatable with a ratchet which isstepped as the relay is energized, the cam being provided with alternatehigh and low portions. After a single energization, the switchingposition is maintained until the relay is again operated and its contacttongues are returned to their original positions. In each cycle ofoperation, A. C. relay 25! is energized twice as will appear from theensuing description.

Now as relay 25! is operated, contact tongue 249 is opened, breaking theoriginal operated circuit path for relay 254 and tongue 281 is closedpreparing a circuit path for the operation of clutch solenoid 36 overconductors 289 and 29! through closed contact tongue 281, throughcontact tongue 284 (when it moves away from A. C. relay 216 as willlater be described) and over conductors 221 and 226 to A. C. lead line224.

The cathode of the photo cell I62 at this time receives an out-of-focusimage through the lens I6! (Figure 15) which is, an integration of thedensity of the negative from which the print is being made, and currentnow flows from the anode which is maintained positive by the currentreceived through resistor R-5 by the action of rectifier tube V!V of thephoto cell I62 to its cathode and causes capacitor 0-2 to discharge. Thetime of discharge of capacitor 0-2 is dependent on the resistor circuitassociated with the particular control switch selected and the averagedensity of the negative which controls current flow to the cathode oftube I62. It should be mentioned that the out-of-focus image projectedupon the cathode of the photo cell I62 is also more advantageous than afocused image for the reason that light might be concentrated at asingle point on the cathode and difierent sections of the cathode mayhave varying electronic discharge characteristics. It is believed thatthe various possible resistance circuits through the control switches220 are readily 11 traceable. It is evident then, that depression of aparticular switch 220 sets up a resistance discharge circuit forcapacitor C2 different than the unselected switches 220.

When capacitor C-Z discharges to a certain point, the grid bias providedon tube V-il is reduced to a point which enables current to flow in theplate circuit of tube V-l I. When this occurs, there is a voltage dropacross resistor R-B which controls the grid of tube V-111. This weakensthe current flow in the plate circuit of tube V-111 to an extent whichresults in the deenergization of D. C. relay 266.

Upon deenergization of D. C. relay 266, the locking circuit 'for relay254 is broken as tongue 2'11 returns to its unattracted position therebyagain closing the charging circuit for timer section 215 extending overconductor 256, readying the charging circuit for capacitor C-2 for thenext operating cycle of the apparatus. Release of relay 266 furtherresults in the deenergization of relays 274 and 216 and solenoids 99,132 and 136 and tongue 213 is opened. Thus, at this point, the platen isreleased, the judging shutter is once more opened, and the light shutteris closed. When relay 214 becomes deenergized, the printing light 151 isextinguished as contact tongue 282 is opened.

As relay 2'16 is released, the previously described circuit for clutchsolenoid 36 is made as tongue 204 falls back to its unattractedposition. The switch operating earns 66, 60 and '11 are thus at thistime released for rotation and in addition the cam 13 functions tooperate the adjustable paper feed mechanism. As cam H rotates, switch280 is opened, insuring that stop lever 46 will be in a position todisengage pawl 48 from ratchet 32 as it completes a single revolution.

Cam switch 261 is opened prior to the closure of cam switch 292 and asthe latter switch is closed, a circuit is made for the operation ofratchet relay 251 as follows: from A. C. line 236, over conductors 242and 241, through the winding of ratchet relay 251, over conductor 293,through closed contact 292, over conductors 229 and 228, through mainswitch 211 and over conductors 22'! and 226 to A. C. line 224. Thus, atthis time, ratchet relay 251 is operated to its originally describedposition and contact tongue 249 moves to its unattracted position toprovide once more the original energizing circuit path for A. C. relay254. Simultaneously with the closure of contact tongue 249, contacttongue 281 which leads to the clutch solenoid 36, is opened. Just at theend of the revolution of the cams, cam switches 261 and 288 are againclosed and the machine is ready for another cycle of operations.

Thus far the invention has been described in connection with the makingof a single print. The means for reproducing multiple exposures for 2, 3or 4 prints will now be described. In Figure 17 is shown three gangswitches 294, 295 and 296 which respectively act as control means forthe purpose of making two, three or four positive prints. Assuming nowthat it is desired to make two positive prints, gang switch 294 isclosed. This results in the formation'of an obvious circuit forindicating lamp 29'! extending over the leads 246 and 241 since, at thistime, contact 296 is closed. Closure of contact 299 is effective inestablishing the following circuit: from A. 0. line 224, over conductors.226 and 221, through the main switch 211, over conductor 228, throughclosed contact 249, over conductor 262, through closed cam switch 261,through closed contact 299, over conductors 301 and 302, then throughwiper 303, conductor 304 to relay 254, conductors 242, 234 and to A. C.line 236. The closing of switch 299 also establishes a circuit throughconductors 301 and 302. To initiate the multiple exposure, switch 248 isclosed and the circuit operates in the first cycle of operation as forsingle exposures. However, the second printing operation will take placeautomatically as brush 303 moves from a dead contact to one that iswired, closing the circuit just described above and operating relay 254as it was previously operated by switch 248, thereby automaticallyinitiating a repeat operation.

The stepping of the brushes 303 will now be explained. When switch 306of gang switch 294 was closed, the following circuit was made whichplaced the stepping solenoid 301 in series with the clutch solenoid 30;from A. C. line 236, over conductors 234 and 201, through the winding ofstepping solenoid 301, over conductors 308 and 309, through closedcontact 306, over conductor 291, to the previously described circuitextending to contact tongue 26! of ratchet relay 251. When brush 31 1 isstepped to the commutator ring 312, the circuit just described willby-pass contact 300 of gang switch 264 as conductor 300 will connectwith conductor 291 over short lead 313.

Thus, on each operation of clutch solenoid 36, stepping solenoid 301will also be operated and brushes 303 will be moved to a new positionand when the next dead contact is encountered by brush 303 of bank 302,the repeat operation will cease. Brush 303 may continue to be stepped asthe printer is operated without effect until the neutral position isreached where it will automatically stop. Of course, as is well known inthis type of switch, the brushes 303 are mounted on the same shaft asbrush 311 and will rotate therewith.

'It is believed that the operation of gang switches 295 and 296 andtheir respective contact banks 314 and 316 is obvious from the foregoingdescription. When switch 295 is operated, lamps 291 and 311 will beilluminated. When switch 296 is operated, lamps 291, 3 11 and 318 willbe illuminated. It should be pointed out again, for the sake of clarity,that since cam switch 261 is closed justat the end of a revolution ofthe cam sleeve, when brush 303 associated with a contact bank being usedis on a wired contact, it will function just as if switch 248 were*reoperated to accomplish another printing cycle of operation.

past the judging glass 104.

While there has been illustrated and described a preferred embodiment'ofthis invention, it :must be understood that the invention is :capable ofconsiderable variation and modification without departing from thespirit of the invention.

Therefore, the invention :should *not be :limited to the precise detailsof constructioniset for.th,hut

should *extend to such variations and modifications as come within thescope of the appended claims.

What is claimed is:

1. In combination, apparatus for the automatic control of exposure inphotographic printing apparatus, a printing paper, printing paperfeeding means for intermittently advancing the printing paper inpredetermined sections, a negative to be printed on sections of saidprinting paper, a first optical system for reproducing on said printingpaper exposed by an image derived from said negative, a second opticalsystem for producing an out-of-focus image of said negative, meanscontrolled by said out-of-focus image for governing the period ofprinting exposure provided by said first mentioned optical system, aplurality of control means for producing multiple exposures of the samenegative, means for selecting one of said control means for synchronoustimed operation to thereby effect the printing of a predetermined numberof positive prints, and means responsive upon the termination of theindividual exposure periods to operate said feeding means for advancinga section of said printing paper into printing position.

2. In combination, apparatus for the automatic control of exposure inphotographic printin apparatus, a printing paper, printing paper feedingmeans to intermittently advance said paper in sections in the path ofsaid first optical system, a negative to be printed, a first opticalsystem for reproducing on said printing paper an image exposed by andderived from said negative, a second optical system for producing anout-offocus image of said negative, means controlled by saidout-of-focus image for governing the time of printin exposure, and aplurality of individually selectable control means for automaticallyeffecting a predetermined number of recycles of synchronized operationof said printing exposure means according to the control means selected,thereby producing a predetermined number of positive prints from thesame negative responsive to the initial actuation of a particularselectable control means.-

3. In combination, apparatus for the automatic control of exposure inphotographic printing apparatus, a negative to be printed, a printingpaper, a lamp for passing light through said negative to said printingpaper, a normally closed light shutter for controlling the passage oflight :from said lamp through said negative to said printing paper, anormally open judging shutter for viewing the condition of saidnegative, an electrical control means including switch means, meansoperative upon the operation of said :switch means for automaticallyclosing said judging shutters, illuminating said light and opening saidlight shutter, means responsive to the average light transmittingcharacteristics of the out-of-focus image produced by said negativeitself for closing said light shutter, extinguishing said light andopening said judging shutter, and paper feeding means responsive to saidlast named means for advancing a new section of said paper into printingposition for a succeeding printing operation.

4. In combination, apparatus for the automatic control of exposure inphotographic printing apparatus, a negative to be printed, a printingpaper, a first optical system including a lamp for passing light throughsaid negative to said printing paper for reproducing on said printingpaper exposed by an image derived from said ne ative, a norma y p n ju gng hutter in the path of the lamp in said first optical system forviewing the condition of said negative, an electrical control meansincluding switch means, means operative upon the operation of saidswitch means for automatically closing said judging shutter,illuminating said light and opening said light shutter, a second opticalsystem for producing an out-of-focus image of said negative, a normallyclosed light shutter in the path of said second optical system forcontrolling the passage of light from said lamp through said negative tosaid printing paper, means responsive to the average light transmittingcharacteristics of the out-of-focus image produced by said negativeitself for closing said light shutter, extinguishing said light andopening said judging shutter, and paper feeding means responsive to saidlast named means for advancing a new section of said paper into printingposition for a succeeding printing operation.

5. In combination, apparatus for the automatic control of exposure inphotographic printing apparatus, a negative to be printed, a printingpaper, a first optical system including a lamp for passing light throughsaid negative to said printing paper for reproducing on said printingpaper exposed by an image derived from said negative, a normally openjudging shutter in the path of the lamp in said first optical system forviewing the condition of said negative, an electrical control meansincluding switch means, means operative upon the operation of saidswitch means for automatically closing said judging shutter,illuminating said light and opening said light shutter, a second opticalsystem for producing an out-of-focus image of said negative, a normallyclosed light shutter in the path of said second optical system forcontroling the passage of light from said lamp through said negative tosaid printing paper, means responsive to the average light transmittingcharacteristics of the out-of-focus image produced by said negativeitself for closing said light shutter, extinguishing said light andopening said judging shutter, paper feeding means responsive to saidlast named means for advancing a new section of said paper into printingposition for a succeeding printing operation, a plurality of selectablecontrol means for automatically producing multiple exposures of the samenegative, and means for selecting one of said control means forsynchronized timed operation of said printing exposure means and saidfeeding means.

EDWIN J. MAKER. JAMES L. GIBSON.

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